Most garden fuschias are notoriously late into leaf and flower, the harder the winter/spring the later they start into growth. Nursery fuschias will have been brought on in geenhouses. If I bring mine into the conservatory and keep them in until late spring they will flower early. If I leave them in a cold place it will be later. Outside can be even later. The upside is that they give masses of blooms in the autumn. Warmth is te key factor.
Light isn't important until leaves start to grow...in fact you can cover an outside fuschia with straw and black polythene until it grows again. Warmth is probably the most important in the springtime when you want active growth, otherwise it will wait for warmer summer days.
After this horrendous summer in my exposed garden, the fuschias are very behind, and one has not even flowered yet !